There exist several different kinds of computer input devices. One kind is a conventional computer mouse. A computer mouse is placed on a support pad. When the mouse is moved over the support pad, the relative movement is detected and transmitted to the computer. Such a mouse is also often equipped with click buttons and a scroll wheel. A problem with this type of input device is that long-time use causes static stress on the fore arm muscles which may lead to stress injuries.
Another kind of computer input devices are so called joysticks. Instead of detecting the relative movement between the computer device and the support pad as with a computer mouse, with a joystick the inclination of a handle is detected and transmitted to the computer. Also a joystick may include buttons or the like for additional functions. One drawback with such a device is that most people experience difficulties to manoeuvre a joystick an high precision applications.
Another known input device, which functions in the same way as a conventional computer mouse and has, relative a joystick, improved precision properties, is a pen-shaped computer mouse. Drawbacks with pen mice are that they are only operable under a limited range of inclinations, which has proven difficult for a normal user to maintain. Consequently, there may be gaps in the stream of information transmitted to the computer. Furthermore, a pen mouse must be moved without rotating it in order to maintain the reference directions. If, for example the pen mouse is rotated 90°, an original longitudinal direction will be interpreted as lateral. Furthermore, a pen mouse has to be repeatedly put down and picked up during normal computer work including operating a keyboard. If the pen mouse is of a wireless type, it may in addition easily get lost on a desk.
A solution to these problems has been presented in WO 01/01233. In the document a computer input device of the kind mentioned in the first paragraph is known. This known device is arranged for wireless transmittal of information regarding the movement of a support element relative to a support pad to a receiving unit. A protrusion is provided on the support element comprising a torsionally rigid, elastic joint. A pen shaped arrangement is connectable to the joint. The support element is designed to be controlled by the pen shaped arrangement. A problem with this known device is that the user experiences insufficient precision. Further, although the known input device constitutes an improvement over conventional input devices, the device is not ergonomically optimal.